Adsorption Property of U(Ⅵ) on Tripolyphosphate-crosslinking Chitosan/Nano-Fe⁰ Composite Membrane

The tripolyphosphate-crosslinking chitosan/nano-Fe⁰ (CS-Fe) composite membrane was prepared for U(Ⅵ) adsorption. The effect of pH on the adsorption of U(Ⅵ) onto CS-Fe, adsorption kinetics and adsorption isotherms were investigated. The results indicate that the adsorption isotherms fit well with the bi-site Langmuir model, with the phosphate groups from CS-Fe as the main sorption sites and nano-Fe⁰ (FeNPs) as the secondary active sites. The adsorption kinetics follows pseudo second-order model, indicating chemisorption as the rate-controlling step. The enhanced adsorption of U(Ⅵ) for CS-Fe (q_m,cal= 208.8 mg/g against q_m,cal=131.6 mg /g for CS) is attributed to the dispersion of FeNPs in chitosan matrix and the redox reaction between the well-dispersed FeNPs and U(Ⅵ).